The OfA form כנם is almost certainly the same word as the BA, with the final unstressed short vowel not indicated in the orthography

The biblical vocalization is inexplicable within Aramaic, and is probably a late tradition; the word apparently having been understood as derived from Hebrew נֶאֱמַר preceded by כ, i.e., "as is said". We assume, rather, (with DISO) that it is derived from the common kn adv. : "thus, so" with an additional adverbial ending in -m as frequently found in the older dialects.